We filled an 8x8 cake pan with milk and added a few drops of food coloring. Mercedes dipped the end of a spoon in liquid dish soap and then in the milk. Instantly the food coloring started swirling around like crazy! To read about the scientific reason behind this, go to: http://www.coolscience.org/CoolScience/KidScientists/tiedyemilk.htm
At age 23 months, we are mostly just interested in making the pretty colors swirl around. =-)
Mercedes also dumped some of the milk into the bowl of dish soap. That was fun to watch too!